Although potential risk of pharmaceuticals and personal care products (PPCPs) and endocrine disrupting compounds (EDCs) and trihalomethanes to humans is small or unconfirmed, it is advisable to remove these wastewater-related contaminants to increase public confidence and acceptance as a precautionary principle and consequently their elimination or reduction during drinking water treatment is warranted. Experiments were conducted using the dual train pilot-scale conventional treatment plant with ozone and ultraviolet/hydrogen peroxide (UV/H2O2) with three different raw water sources. Reductions of trihalomethanes-formation potentials (THM-FPs) were 8–52%. Ozone was found to decrease THM-FPs while UV/H2O2 was found to increase THM-FPs in most of the experiments under experimental conditions. Conventional treatment poorly removed the selected PPCPs and EDCs while ozone + conventional treatment provided excellent removal. Conventional + UV/H2O2 treatment also demonstrated effective removal. However, removal of PPCPs and EDCs by conventional + UV/H2O2 treatment provided lower efficacy for Sites B and C, likely due to the presence of scavengers such as organics, bicarbonates, carbonates and particles.
{"title":"Evaluations of conventional, ozone and UV/H2O2 for removal of emerging contaminants and THM-FPs","authors":"Devendra Borikar, M. Mohseni, S. Jasim","doi":"10.2166/WQRJC.2014.018","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.018","url":null,"abstract":"Although potential risk of pharmaceuticals and personal care products (PPCPs) and endocrine disrupting compounds (EDCs) and trihalomethanes to humans is small or unconfirmed, it is advisable to remove these wastewater-related contaminants to increase public confidence and acceptance as a precautionary principle and consequently their elimination or reduction during drinking water treatment is warranted. Experiments were conducted using the dual train pilot-scale conventional treatment plant with ozone and ultraviolet/hydrogen peroxide (UV/H2O2) with three different raw water sources. Reductions of trihalomethanes-formation potentials (THM-FPs) were 8–52%. Ozone was found to decrease THM-FPs while UV/H2O2 was found to increase THM-FPs in most of the experiments under experimental conditions. Conventional treatment poorly removed the selected PPCPs and EDCs while ozone + conventional treatment provided excellent removal. Conventional + UV/H2O2 treatment also demonstrated effective removal. However, removal of PPCPs and EDCs by conventional + UV/H2O2 treatment provided lower efficacy for Sites B and C, likely due to the presence of scavengers such as organics, bicarbonates, carbonates and particles.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.018","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67981252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sandra M. Brasfield, L. Hewitt, L. Chow, S. Batchelor, H. Rees, Z. Xing, K. Munkittrick
Non-point source discharges, such as agricultural runoff, are often complex mixtures of chemical and non-chemical stressors. The complexity of runoff is compounded by its sporadic releases and few studies have attempted to assess the impacts of runoff on aquatic biota. In this study, an effects based approach was used to examine survival and reproduction of slimy sculpin ( Cottus cognatus ) in the intensive potato-farming areas of northwestern New Brunswick, Canada. Using non-lethal methods, fish were collected during the ice-free months through a gradient of agricultural intensity. These data were correlated with waterborne levels of pesticides, water temperatures and precipitation data. Results indicate that both adult and young-of-the-year (YOY) fish are longer and heavier in the downstream sites draining areas of higher agricultural intensity. Precipitation has a significant negative relationship with %YOY in the agricultural areas but not in the upstream forested area, indicating that contaminants are present in runoff caused by intensive rainfall events. Our results indicate that YOY sculpin may be at higher risk in the agricultural areas in years of heavier summer rains where peaks in pesticide levels occur. This study expands the existing knowledge base and development of non-lethal methods to define cause–effect relationships.
{"title":"Assessing the contribution of multiple stressors affecting small-bodied fish populations through a gradient of agricultural inputs in northwestern New Brunswick, Canada","authors":"Sandra M. Brasfield, L. Hewitt, L. Chow, S. Batchelor, H. Rees, Z. Xing, K. Munkittrick","doi":"10.2166/WQRJC.2014.126","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.126","url":null,"abstract":"Non-point source discharges, such as agricultural runoff, are often complex mixtures of chemical and non-chemical stressors. The complexity of runoff is compounded by its sporadic releases and few studies have attempted to assess the impacts of runoff on aquatic biota. In this study, an effects based approach was used to examine survival and reproduction of slimy sculpin ( Cottus cognatus ) in the intensive potato-farming areas of northwestern New Brunswick, Canada. Using non-lethal methods, fish were collected during the ice-free months through a gradient of agricultural intensity. These data were correlated with waterborne levels of pesticides, water temperatures and precipitation data. Results indicate that both adult and young-of-the-year (YOY) fish are longer and heavier in the downstream sites draining areas of higher agricultural intensity. Precipitation has a significant negative relationship with %YOY in the agricultural areas but not in the upstream forested area, indicating that contaminants are present in runoff caused by intensive rainfall events. Our results indicate that YOY sculpin may be at higher risk in the agricultural areas in years of heavier summer rains where peaks in pesticide levels occur. This study expands the existing knowledge base and development of non-lethal methods to define cause–effect relationships.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.126","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67980893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water distribution networks (WDNs) are vulnerable to various types of contamination events that may have impacts on human health and the environment. Therefore, there is a growing need to design an effective monitoring system. Due to the cost of both placing and maintaining the sensors, their numbers must be limited. This constraint makes the sensor deployment locations crucial in water monitoring systems. Several methodologies have been suggested in the past two decades by different researchers for placement of sensors in WDNs. These methodologies differ in many ways depending on the number of objectives, solution methodology, concentration level of contaminant considered, type of simulation, and so on. In this paper, various methodologies have been broadly classified based on the number of performance objectives as single and multi-objective sensor location problems. Some of the features of these methodologies are also mentioned to help understand the advantages of a particular method over other methods. A critical review of literature is presented. Some of the issues on which a consensus is being developed amongst researchers are discussed and recommendations are made with a view to suggest future research needs for sensor network design of large WDNs.
{"title":"A critical review of sensor location methods for contamination detection in water distribution networks","authors":"S. Rathi, Rajesh Gupta","doi":"10.2166/WQRJC.2014.011","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.011","url":null,"abstract":"Water distribution networks (WDNs) are vulnerable to various types of contamination events that may have impacts on human health and the environment. Therefore, there is a growing need to design an effective monitoring system. Due to the cost of both placing and maintaining the sensors, their numbers must be limited. This constraint makes the sensor deployment locations crucial in water monitoring systems. Several methodologies have been suggested in the past two decades by different researchers for placement of sensors in WDNs. These methodologies differ in many ways depending on the number of objectives, solution methodology, concentration level of contaminant considered, type of simulation, and so on. In this paper, various methodologies have been broadly classified based on the number of performance objectives as single and multi-objective sensor location problems. Some of the features of these methodologies are also mentioned to help understand the advantages of a particular method over other methods. A critical review of literature is presented. Some of the issues on which a consensus is being developed amongst researchers are discussed and recommendations are made with a view to suggest future research needs for sensor network design of large WDNs.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67981105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, the performances of the decision tree forest and group method of data handling for evaluation scale of the severity (SEV) of ill effect for fishes were investigated. The independent variables were concentration of suspended sediment (SS), species, life stage, and duration of exposure. This study is based on 198 data of aquatic ecosystem quality over a wide range of sediment concentrations (1–500,000 mg SS/L) and durations of exposure (1–35,000 h). Results showed that exposure duration is the most important factor on SEV, and based on the results, this alternative approach is better than traditional regression models with a higher recognition rate, forecast accuracy, and strong practical value.
{"title":"Evaluation of effect of sediment on aquatic ecosystems using decision tree forest and group method of data handling.","authors":"H. Khakzad, V. I. Elfimov","doi":"10.2166/WQRJC.2014.020","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.020","url":null,"abstract":"In this study, the performances of the decision tree forest and group method of data handling for evaluation scale of the severity (SEV) of ill effect for fishes were investigated. The independent variables were concentration of suspended sediment (SS), species, life stage, and duration of exposure. This study is based on 198 data of aquatic ecosystem quality over a wide range of sediment concentrations (1–500,000 mg SS/L) and durations of exposure (1–35,000 h). Results showed that exposure duration is the most important factor on SEV, and based on the results, this alternative approach is better than traditional regression models with a higher recognition rate, forecast accuracy, and strong practical value.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67981294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aaron Fernandes, Y. Lawryshyn, J. Gibson, R. Farnood
It is well accepted that the breakage of wastewater suspended particles (flocs) can lead to better disinfection of effluent, especially when utilizing ultraviolet irradiation as the disinfection method. In this work, the breakage of wastewater flocs in orifice flow was investigated through numerical simulations. The strain rate along particle paths was estimated using computational fluid dynamics. Assuming that particle breakage occurs if the maximum strain rate experienced by the particle exceeds a critical threshold value, breakage of wastewater particles was predicted. The effectiveness of the model was supported by simple experiments. Based on the numerical simulations, under the same nominal orifice strain rate, particle breakage was higher in single-orifice systems compared to that of multi-orifice systems. This finding was further confirmed through experimentation. Furthermore, simulation results revealed that while single-orifice systems were the preferred choice for the breakage of strong particles, multi-orifice systems might be more effective in breaking ‘weak’ particles.
{"title":"Experimental and numerical investigation of the breakage of wastewater flocs in orifice flow.","authors":"Aaron Fernandes, Y. Lawryshyn, J. Gibson, R. Farnood","doi":"10.2166/WQRJC.2014.030","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.030","url":null,"abstract":"It is well accepted that the breakage of wastewater suspended particles (flocs) can lead to better disinfection of effluent, especially when utilizing ultraviolet irradiation as the disinfection method. In this work, the breakage of wastewater flocs in orifice flow was investigated through numerical simulations. The strain rate along particle paths was estimated using computational fluid dynamics. Assuming that particle breakage occurs if the maximum strain rate experienced by the particle exceeds a critical threshold value, breakage of wastewater particles was predicted. The effectiveness of the model was supported by simple experiments. Based on the numerical simulations, under the same nominal orifice strain rate, particle breakage was higher in single-orifice systems compared to that of multi-orifice systems. This finding was further confirmed through experimentation. Furthermore, simulation results revealed that while single-orifice systems were the preferred choice for the breakage of strong particles, multi-orifice systems might be more effective in breaking ‘weak’ particles.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.030","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67980849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carrie L. Knatz, S. Rafferty, Anthony Delescinskis
In the design of water and wastewater treatment plants, proper flow and solids distribution can be as critical as process design considerations. Insufficient treatment and even plant failures can result from unequal and unmanageable flow and solids distribution. Computational fluid dynamics (CFD) modeling is a valuable tool in the evaluation of flow distribution to multiple units within a treatment process. This article reviews the benefits achieved by performing a CFD analysis of an Infilco high-rate dissolved air flotation (DAF) influent channel prior to finalizing the design of the plant. The CFD model was used to optimize the DAF influent channel configuration with respect to flow distribution to 10 identical process units that were inserted into an existing facility footprint. For the initial configurations modeled, the largest deviation of flow rate to an individual DAF unit was over 60%. Using CFD, design engineers developed a DAF influent channel configuration predicted to achieve less than 10% deviation. The upgraded facility is constructed and in service and the results of the CFD model were confirmed using actual turbidity data, which indicate that the solids are evenly distributed to the DAF process trains.
{"title":"Optimization of water treatment plant flow distribution with CFD modeling of an influent channel","authors":"Carrie L. Knatz, S. Rafferty, Anthony Delescinskis","doi":"10.2166/WQRJC.2014.024","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.024","url":null,"abstract":"In the design of water and wastewater treatment plants, proper flow and solids distribution can be as critical as process design considerations. Insufficient treatment and even plant failures can result from unequal and unmanageable flow and solids distribution. Computational fluid dynamics (CFD) modeling is a valuable tool in the evaluation of flow distribution to multiple units within a treatment process. This article reviews the benefits achieved by performing a CFD analysis of an Infilco high-rate dissolved air flotation (DAF) influent channel prior to finalizing the design of the plant. The CFD model was used to optimize the DAF influent channel configuration with respect to flow distribution to 10 identical process units that were inserted into an existing facility footprint. For the initial configurations modeled, the largest deviation of flow rate to an individual DAF unit was over 60%. Using CFD, design engineers developed a DAF influent channel configuration predicted to achieve less than 10% deviation. The upgraded facility is constructed and in service and the results of the CFD model were confirmed using actual turbidity data, which indicate that the solids are evenly distributed to the DAF process trains.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.024","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67981306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The disinfection characteristics of an open channel ultra-violet (UV) disinfection reactor is investigated numerically. The computational fluid dynamics (CFD) model used in this study is based on the volume of fluid (VOF) method to capture the water–air interface. The Lagrangian particle tracking method is used to calculate the microbial particle trajectory and the discrete ordinate (DO) model is used to calculate the UV intensity field inside the reactor. A commercial CFD software package ANSYS FLUENT is used to solve the governing equations. Custom user defined functions (UDFs) are developed to calculate the UV doses. A post-processor is developed in MATLAB to implement the inactivation kinetics of the microbes. The post-processor provides the probabilistic dose distribution and reduction equivalent dose (RED) values achievable in the reactor. The numerical predictions are compared with available experimental data to validate the CFD model. A parametric study is performed to understand the effects of different parameters on disinfection performance of the reactor. The low/high dosed particle trajectories, which can provide an insight for hydraulic and optical characteristics of the reactor for possible design improvements, are identified.
{"title":"Computational fluid dynamics simulation and parametric study of an open channel ultra-violet wastewater disinfection reactor","authors":"R. Saha, M. Ray, Chao Zhang","doi":"10.2166/WQRJC.2014.034","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.034","url":null,"abstract":"The disinfection characteristics of an open channel ultra-violet (UV) disinfection reactor is investigated numerically. The computational fluid dynamics (CFD) model used in this study is based on the volume of fluid (VOF) method to capture the water–air interface. The Lagrangian particle tracking method is used to calculate the microbial particle trajectory and the discrete ordinate (DO) model is used to calculate the UV intensity field inside the reactor. A commercial CFD software package ANSYS FLUENT is used to solve the governing equations. Custom user defined functions (UDFs) are developed to calculate the UV doses. A post-processor is developed in MATLAB to implement the inactivation kinetics of the microbes. The post-processor provides the probabilistic dose distribution and reduction equivalent dose (RED) values achievable in the reactor. The numerical predictions are compared with available experimental data to validate the CFD model. A parametric study is performed to understand the effects of different parameters on disinfection performance of the reactor. The low/high dosed particle trajectories, which can provide an insight for hydraulic and optical characteristics of the reactor for possible design improvements, are identified.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.034","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67980911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A computational model for simulating the performance of immobilized photocatalytic ultraviolet (UV) reactors used for water treatment was developed, experimentally evaluated, and applied to reactor design optimization. This model integrated hydrodynamics, species mass transport, chemical reaction kinetics, and irradiance distribution within the reactor. Among different hydrodynamic models evaluated against experimental data, the laminar, Abe–Kondoh–Nagano, and Reynolds stress turbulence models showed better performance (errors <5%, 12%, and 20%, respectively) in terms of external mass transfer and surface reaction prediction capabilities at different hydrodynamic conditions. A developed finite-volume-based UV lamp emission model was able to predict, with errors of less than 5%, near- and far-field irradiance measurements. Combining all these models, the integrated computational fluid dynamics (CFD)-based model was able to successfully predict the photocatalytic degradation rate of model pollutants (benzoic acid and 2,4-D) in various configurations of annular reactors and UV lamp sizes, over a wide range of hydrodynamic conditions (350 < Re < 11,000). In addition, the integrated model was used in combination with a Taguchi design of experiments method to perform reactor design optimization. Following this approach, a base case annular reactor design was modified to obtain a 50% more efficient design.
建立了用于水处理的固定化光催化紫外(UV)反应器性能的模拟计算模型，并进行了实验评估，并将其应用于反应器设计优化。该模型综合了反应器内的流体动力学、物质质量传递、化学反应动力学和辐照度分布。在不同的水动力模型中，层流、Abe-Kondoh-Nagano和Reynolds应力湍流模型在不同水动力条件下的外传质和表面反应预测能力表现较好(误差分别<5%、12%和20%)。开发的基于有限体积的紫外灯发射模型能够以小于5%的误差预测近场和远场辐照度测量。结合所有这些模型，基于计算流体动力学(CFD)的集成模型能够成功预测模型污染物(苯甲酸和2,4- d)在各种环形反应器配置和紫外灯尺寸下的光催化降解率，在广泛的流体动力条件下(350 < Re < 11,000)。此外，将该集成模型与田口设计的实验方法相结合，进行了反应器设计优化。根据这种方法，对基本情况下的环形反应堆设计进行了修改，使设计效率提高了50%。
{"title":"Computational modeling of UV photocatalytic reactors: model development, evaluation, and application.","authors":"J. E. Duran, M. Mohseni, F. Taghipour","doi":"10.2166/WQRJC.2014.031","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.031","url":null,"abstract":"A computational model for simulating the performance of immobilized photocatalytic ultraviolet (UV) reactors used for water treatment was developed, experimentally evaluated, and applied to reactor design optimization. This model integrated hydrodynamics, species mass transport, chemical reaction kinetics, and irradiance distribution within the reactor. Among different hydrodynamic models evaluated against experimental data, the laminar, Abe–Kondoh–Nagano, and Reynolds stress turbulence models showed better performance (errors <5%, 12%, and 20%, respectively) in terms of external mass transfer and surface reaction prediction capabilities at different hydrodynamic conditions. A developed finite-volume-based UV lamp emission model was able to predict, with errors of less than 5%, near- and far-field irradiance measurements. Combining all these models, the integrated computational fluid dynamics (CFD)-based model was able to successfully predict the photocatalytic degradation rate of model pollutants (benzoic acid and 2,4-D) in various configurations of annular reactors and UV lamp sizes, over a wide range of hydrodynamic conditions (350 < Re < 11,000). In addition, the integrated model was used in combination with a Taguchi design of experiments method to perform reactor design optimization. Following this approach, a base case annular reactor design was modified to obtain a 50% more efficient design.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.031","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67980862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Crapulli, D. Santoro, M. Sasges, Shaunak Ray, Housyn Mahmoud, A. Ray
The use of ultraviolet light for inactivation of pathogens is an engrained, low-cost, eco-friendly method for disinfection of nearly transparent (UVT254 > 30%/cm) contaminated fluids for which a standard-collimated beam apparatus is typically used for measurement of intrinsic inactivation kinetics. However, such a device cannot be used for low ultraviolet transmittance (UVT254 < 30%/cm) and nearly opaque (UVT254 < 10%/cm) fluids because of the lack of sufficient mixing and intrinsic inactivation kinetics controlled by dose distribution and mass-transfer effects. In this paper, a computational fluid dynamics (CFD) model was used to determine the validity regime for accurate ultraviolet inactivation kinetics studies in low transmittance and nearly opaque fluids when a new Taylor–Couette collimated beam apparatus, which exploits flow instability through the formation of toroidal counter-rotating vortices, is used for irradiations. A Taylor number of ∼ 46,500 was sufficient to overcome the very short UV light penetration at UVT254 ∼ 0.001%/cm as long as the log10 reduction value was used as controlling parameter. Specifically, it was identified that, in case of first-order inactivation kinetics, the applied average dose (AD) should not be higher than three times the dose required for one log10 inactivation (also known as D 10) in order to generate data for accurate kinetic studies.
{"title":"Quantifying ultraviolet inactivation kinetics in nearly opaque fluids","authors":"F. Crapulli, D. Santoro, M. Sasges, Shaunak Ray, Housyn Mahmoud, A. Ray","doi":"10.2166/WQRJC.2014.032","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.032","url":null,"abstract":"The use of ultraviolet light for inactivation of pathogens is an engrained, low-cost, eco-friendly method for disinfection of nearly transparent (UVT254 > 30%/cm) contaminated fluids for which a standard-collimated beam apparatus is typically used for measurement of intrinsic inactivation kinetics. However, such a device cannot be used for low ultraviolet transmittance (UVT254 < 30%/cm) and nearly opaque (UVT254 < 10%/cm) fluids because of the lack of sufficient mixing and intrinsic inactivation kinetics controlled by dose distribution and mass-transfer effects. In this paper, a computational fluid dynamics (CFD) model was used to determine the validity regime for accurate ultraviolet inactivation kinetics studies in low transmittance and nearly opaque fluids when a new Taylor–Couette collimated beam apparatus, which exploits flow instability through the formation of toroidal counter-rotating vortices, is used for irradiations. A Taylor number of ∼ 46,500 was sufficient to overcome the very short UV light penetration at UVT254 ∼ 0.001%/cm as long as the log10 reduction value was used as controlling parameter. Specifically, it was identified that, in case of first-order inactivation kinetics, the applied average dose (AD) should not be higher than three times the dose required for one log10 inactivation (also known as D 10) in order to generate data for accurate kinetic studies.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.032","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67980903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work uses computational fluid dynamics (CFD) as a design tool in wastewater treatment modeling practice to assess the specific use of the hydrojets in oxidation ditches. The hydrodynamics and the residence time distribution in an oxidation ditch are simulated using several turbulence models: Reynolds averaged Navier–Stokes simulations (RANS) and unsteady RANS with the standard k ‒ e model; and large eddy simulation with the Smagorinsky subgrid scale model. The influence of the mesh resolution, of the hydrojets placement on the oxidation ditch hydrodynamics and on the energy demand for mixing is assessed. Finally, the effect of the turbulence models on the macromixing data, which can be implemented in the activated sludge model, is also evaluated.
{"title":"Modeling of the hydrodynamics and energy expenditure of oxidation ditch aerated with hydrojets using CFD codes","authors":"A. Karpinska, M. Dias, R. Boaventura, R. Santos","doi":"10.2166/WQRJC.2014.036","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.036","url":null,"abstract":"This work uses computational fluid dynamics (CFD) as a design tool in wastewater treatment modeling practice to assess the specific use of the hydrojets in oxidation ditches. The hydrodynamics and the residence time distribution in an oxidation ditch are simulated using several turbulence models: Reynolds averaged Navier–Stokes simulations (RANS) and unsteady RANS with the standard k ‒ e model; and large eddy simulation with the Smagorinsky subgrid scale model. The influence of the mesh resolution, of the hydrojets placement on the oxidation ditch hydrodynamics and on the energy demand for mixing is assessed. Finally, the effect of the turbulence models on the macromixing data, which can be implemented in the activated sludge model, is also evaluated.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.036","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67980981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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